The revelation is based on a classified intelligence budget provided to the paper by fugitive leaker Edward Snowden, as well as on interviews with former United States officials.

The Post also reported that, under a US$652 million project code-named "GENIE," US specialists hack foreign computer networks to secretly put them under American control.

This involves placing "covert implants" in computers, routers and firewalls, it said, adding that by the end of the year, "GENIE" is projected to control at least 85,000 "malware" plug-ins in machines around the globe.

That compares with just more than 21,200 in 2008, the Post reported, citing the intelligence budget. "The documents provided by Snowden and interviews with US officials describe a campaign of computer intrusions that is far broader and more aggressive than previously understood," the daily said.

Of the 231 "offensive operations" conducted in 2011, nearly 75 per cent were against top-priority targets that the Post, citing former officials, said included "adversaries such as Iran, Russia, China and North Korea, and activities such as nuclear non-proliferation."

The paper said US intelligence services make "routine use" of government-constructed malware around the globe that "differs little in function from the 'advanced persistent threats' that US officials attribute to China."

However, while an unnamed National Security Agency spokesman confirmed to the Post that the Defence Department does engage in computer network exploitation, the paper also quoted him as saying that, unlike China, "the department does not engage in economic espionage in any domain, including cyber."

Snowden, a former US National Security Agency contractor, was granted temporary asylum in Russia on August 1.

He is wanted by Washington on espionage charges linked to media disclosures about US surveillance programmes.

Snowden stay at consulate denied

A lawyer for US intelligence leaker Edward Snowden has denied reports that the fugitive had stayed at the Russian consulate in Hong Kong before his arrival in Moscow, according to an interview published yesterday.

"Edward told me that he never visited any diplomatic missions and that all this is inaccurate. He never had any talks with our diplomats while in Hong Kong," Anatoly Kucherena told the Kommersant newspaper.

Last Monday Kommersant, citing a source close to Snowden, said he had spent several days at the Russian consulate in Hong Kong before flying to Moscow.

In the interview published yesterday, however, Snowden's lawyer said "he and his friends stayed at a hotel there ... He understood he is being chased, so he moved often."

Snowden ended up spending more than a month in Sheremetyevo International Airport in Moscow.